Precise engineering of quantum dot array coupling through their barrier widths

Resumen del trabajo presentado a la 13th European Conference on Surface Crystallography and Dynamics, celebrada en Donostia-San Sebastián (España) del 19 al 21 de junio de 2017.
Quantum dot (QD) arrays on surfaces, generated through molecular self-assembly processes, have so far provided researchers with a vast playground to study the electronic properties of new and exotic 2D materials in ultra-high-vacuum (UHV) conditions. By selecting the proper molecular constituents (tectons) and substrate, long-range ordered, periodic and robust nanoporous networks have been achieved, ranging from hydrogen-bonded to metal-organic structures. Not only do they stand out as ideal templates for nanopatterning, but also as adequate candidates for studying fundamental physical phenomena such as confinement through the scattering of two-dimensional electron gases (2DEGs). Indeed, confinement tunability has already been accomplished by varying the pore (i.e. quantum dot) dimensions, geometrical shape and molecule substrate interactions. In addition, inter-dot coupling has been shown by photoemission through the generation of new dispersive bands that can be modulated through thermodynamics and the condensation of guest elements (Xe atoms). To date, the modification of 2DEGs through inter-dot barrier width variations has not been experimentally demonstrated. Herein, sustained upon a combination of local scanning probes (STM/STS/AFM), angle resolved photoemission spectroscopy (ARPES) and extended model calculations, we show that we can precisely engineer the inter-dot barrier width by substitution of a single atom in a haloaromatic compound. As a result, we tune the confinement properties at each nanopore affecting the degree of QD intercoupling both on bulk and thin Ag films alike. These findings pave the way to reach full control over 2DEGs with the prospect of becoming key for future electronic devices.